"The conventional method of transferring optical brighteners or bluing agents to fabric is by adding the optical brighteners or bluing agents to the wash water along with the detergent. Generally, optical brighteners and bluing agents are not present in bleach, particularly liquid bleach, since the liquid bleach has a strong tendency to oxidize and destroy the dyes with concurrent reduction in bleaching strength. Alternative approaches involving addition of bleach stable inorganic pigments to liquid hypochlorite bleach to effect bluing have also been unsuccessful generally because the pigment particles have a tendency to settle out of suspension." Quoted from GB No. 2,100,307A, Dec. 22, 1982 (The Clorox Co.)
U.S. Pat. No. 4,271,030, Brierley et al., issued June 2, 1981, discloses a colored liquid hypochlorite bleach composition primarily designed for cleaning lavatory pans. The composition contains Ultramarine Blue (UMB) suspended in a flocculate, which is preferably made by reacting a soap or synthetic surfactant with calcium ions. Such a composition which contains a calcium floc is undesirable for laundry cleaning because the calcium floc will deposit on the fabric. (Also, a linear alkylbenzene sulfonate (LAS)/hypochlorite floc alone will not support an effective amount of Ultramarine Blue pigment at an LAS level desirable for an aqueous laundry bleach composition.) This '030 patent does not teach the essential optical brightener used in the present invention. It should also be noted that Ultramarine Blue pigment is distinguished from that essential optical brightener both chemically and physically and is not interchangeable.
U.S. Pat. No. 4,526,700, Hensley & Kitko, issued July 2, 1985, teaches the essential optical brightener technology to maintain physical stability in a nonpigmented system, but does not teach the buffer technology used to improve physical stability of flocculated bleach systems presented by this invention.
It is an object of the present invention to prepare a superior aqueous hypochlorite laundry bleach with suspended inorganic pigments, without calcium soap or the like.